PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       fstat — get file status

SYNOPSIS

       #include <sys/stat.h>

       int fstat(int fildes, struct stat *buf);

DESCRIPTION

       The  fstat()  function  shall  obtain  information about an open file associated with the file descriptor
       fildes, and shall write it to the area pointed to by buf.

       If fildes references a shared memory object, the  implementation  shall  update  in  the  stat  structure
       pointed  to  by  the  buf argument the st_uid, st_gid, st_size, and st_mode fields, and only the S_IRUSR,
       S_IWUSR, S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH file permission bits need be valid.   The  implementation
       may update other fields and flags.

       If fildes references a typed memory object, the implementation shall update in the stat structure pointed
       to by the buf argument the st_uid, st_gid, st_size, and st_mode fields, and only  the  S_IRUSR,  S_IWUSR,
       S_IRGRP,  S_IWGRP, S_IROTH, and S_IWOTH file permission bits need be valid. The implementation may update
       other fields and flags.

       The buf argument is a pointer to a stat structure, as defined in <sys/stat.h>, into which information  is
       placed concerning the file.

       For  all  other file types defined in this volume of POSIX.1‐2017, the structure members st_mode, st_ino,
       st_dev, st_uid, st_gid, st_atim, st_ctim, and st_mtim shall have meaningful values and the value  of  the
       st_nlink member shall be set to the number of links to the file.

       An  implementation  that  provides  additional  or  alternative file access control mechanisms may, under
       implementation-defined conditions, cause fstat() to fail.

       The fstat() function shall update any time-related fields (as described in the Base Definitions volume of
       POSIX.1‐2017, Section 4.9, File Times Update), before writing into the stat structure.

RETURN VALUE

       Upon  successful  completion,  0  shall  be  returned.  Otherwise,  -1 shall be returned and errno set to
       indicate the error.

ERRORS

       The fstat() function shall fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       EIO    An I/O error occurred while reading from the file system.

       EOVERFLOW
              The file size in bytes or the number of blocks allocated to the file or  the  file  serial  number
              cannot be represented correctly in the structure pointed to by buf.

       The fstat() function may fail if:

       EOVERFLOW
              One of the values is too large to store into the structure pointed to by the buf argument.

       The following sections are informative.

EXAMPLES

   Obtaining File Status Information
       The  following  example shows how to obtain file status information for a file named /home/cnd/mod1.  The
       structure variable buffer is defined for the stat structure.  The  /home/cnd/mod1  file  is  opened  with
       read/write privileges and is passed to the open file descriptor fildes.

           #include <sys/types.h>
           #include <sys/stat.h>
           #include <fcntl.h>

           struct stat buffer;
           int         status;
           ...
           fildes = open("/home/cnd/mod1", O_RDWR);
           status = fstat(fildes, &buffer);

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fstatat()

       The Base Definitions volume of POSIX.1‐2017, Section 4.9, File Times Update, <sys_stat.h>, <sys_types.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE  and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .